An integrative study to determine the Bioavaiiability of heavy metals in the soil

摘要

Studying the distribution and availability of heavy metals in the soil has a great importance in assessing environmental quality. This study aims to a) Assess the level of Cadmium(Cd), lead (Pb) and Nickel(Ni) contamination in different soils from theprovince of Basra in southern Iraq; b) determine the available form of the studied metal using different extraction methods, namely (diethylene - triamine acid extraction method, and fumigation-extraction(chloroform-labile metals); and c) determined thepotential dependence of the physiochemical properties of soil. The means of the total heavy metal content for Cd, and Pb were recorded as (0.381 mg.kg~(-1) and 28.933 mg.kg~(-1) ), respectively, which were higher than the levels reported in the standardrange, suggesting some degree of pollution with these metals. Meanwhile, the total heavy metal content of nickel (Ni) was within the range (4.227 mg-kg~(-1)). However, the available forms of heavy metals were extremely low, suggesting that the availability of heavy metals to the organism would be minimal under current conditions. Results also showed that the difference in the available form of metals according to the different extraction methods used, was less for the biological method (0.057, 3.007 and 0. 657 mg-kg~(-1)) compared with the chemical (0.060, 4.779 and 1.272 mg-kg~(-1)) for Cd, Pb and Ni respectively. The results suggested that chemical and biological metals forms should be considered as a complementary technique rather thari an alternative m evaluating the metal bioavailability from different pollution sources. The results indicated weak or lack of significant correlations between heavy metals and total organic carbon, electrical conductivity and pH, indicating that the activity of these metals may be affected by other factors.